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Design Of Light

The sun is probably the one thing we see most often throughout our lives. Whenever we raise our sight to
the sky during the day, we can see its dazzling light. If someone were
to come up and ask "What good is the sun? We would probably reply
without even a thought that the sun gives us light and heat. That
answer, although a bit superficial, would be correct.

But does the sun just "happen" to
radiate light and heat for us? Is it accidental and unplanned? Or is
the sun specially designed for us? Could this great ball of fire in the
sky be a gigantic "lamp" that was created so as to meet our exact
needs?

Recent research indicates that the
answer to the last two questions is "yes". "Yes" because in sunlight
there is a design that inspires amazement

The Right Wavelength

Both light and heat are different manifestations of electromagnetic radiation. In all its manifestations, electromagnetic
radiation moves through space in waves similar to those created when a
stone is thrown into a lake. And just as the ripples created by the
stone may have different heights and the distances between them may
vary, electromagnetic radiation also has different wavelengths.

The analogy shouldn't be taken too far
however because there are huge differences in the wavelengths of
electromagnetic radiation. Some are several kilometers long while
others are shorter than a billionth of a centimeter and the other
wavelengths are to be found in a smooth, unbroken spectrum everywhere
in between. To make things easier, scientists divide this spectrum up
according to wavelength and they assign different names to different
parts of it. The radiation with the shortest wavelength (one-trillionth
of a centimeter) for example is called "gamma rays": these rays pack
tremendous amounts of energy. The longest wavelengths are called "radio
waves": they can be several kilometers long but carry very little
energy. (One result of this is that radio waves are quite harmless to
us while exposure to gamma rays can be fatal.) Light is a form of
electromagnetic radiation that lies between these two extremes.

The first thing to be noticed about
the electromagnetic spectrum is how broad it is: the longest wavelength
is 10 25 times the size of the shortest one. Written out in full, 10 25
looks like this:

10,000,000,000,000,000,000,000,000

A number that big
is pretty meaningless by itself. Let's make a few comparisons. For
example, in 4 billion years (the estimated age of the earth) there are
about 10 17 seconds. If you wanted to count from 1 to 10 25 and did so
at the rate of one number a second nonstop, day and night, it would
take you 100 million times longer than the age of the earth! If we were
to build a pile of 10 25 playing cards, we would end up with a stack
stretching halfway across the observable universe.

This is the vast spectrum over which
the different wavelengths of the universe's electromagnetic energy
extend. Now the curious thing about this is that the electromagnetic
energy radiated by our sun is restricted to a very, very narrow section
of this spectrum. 70% of the sun's radiation has wavelengths between
0.3 and 1.50 microns and within that narrow band there are three types
of light: visible light, near-infrared light, and ultraviolet light.

Three
kinds of light might seem quite enough but all three combined make up
an almost insignificant section of the total spectrum. Remember our 10
25 playing cards extending halfway across the universe? Compared with
the total, the width of the band of light radiated by the sun
corresponds to just one of those cards!

Why should sunlight be limited to such
a narrow range? The answer to that question is crucial because the only
radiation that is capable of supporting life on earth is the kind that
has wavelengths falling within this narrow range.

In Energy and the Atmosphere, the
British physicist Ian Campbell addresses this question and says "That
the radiation from the sun (and from many sequence stars) should be
concentrated into a minuscule band of the electromagnetic spectrum
which provides precisely the radiation required to maintain life on
earth is very remarkable." According to Campbell , this situation is
"staggering".(1) Let us now examine this "staggering design of light"
more closely.

From Ultraviolet To Infrared

We said that there was a range of 1:10
25 in the sizes of the longest and shortest electromagnetic
wavelengths. We also said that the amount of energy that was carried
depended upon the wavelength: shorter wavelengths pack more energy than
longer ones. Another difference has to do with how radiation at
different wavelengths interacts with matter.

The shortest forms of radiation are
called (in increasing order of wavelength) "gamma rays", "X-rays", and
"ultraviolet light". They have the ability to split atoms because they
are so highly energized. All three can cause molecules-especially
organic molecules-to break up. In effect, they tear matter apart at the
atomic or molecular level.

Radiation with wavelengths longer than
visible light begins at infrared and extends up to radio waves. Its
impact upon matter is less serious because the energy it conveys is not
as great.

The "impact upon matter" that we spoke
of has to do with chemical reactions. A significant number of chemical
reactions can take place only if energy is added to the reaction. The
energy required to start a chemical reaction is called its "energy
threshold". If the energy is less than this threshold, the reaction
will never start and if it is more, it is of no good: in either case,
the energy will have been wasted.

In the whole electromagnetic spectrum,
there is just one little band that has the energy to cross this
threshold exactly. Its wavelengths range between 0.70 microns and 0.40
microns and if you'd like to see it, you can: just raise your head and
look around-it's called "visible light". This radiation causes chemical
reactions to take place in your eyes and that is why you are able to
see.

The radiation known as "visible light"
makes up 41% of sunlight even though it occupies less than 1/10 25 of
the whole electromagnetic spectrum. In his famous article "Life and
Light", which appeared in Scientific American, the renowned physicist
George Wald considered this matter and wrote "the radiation that is
useful in prompting orderly chemical reactions comprises the great bulk
of that of our sun."(2)

That the sun should radiate light so exactly right for life is indeed an extraordinary example of design.

Is the rest of the light the sun radiates good for anything?

When we look at this part of the light
we see that a large part of solar radiation falling outside the range
of visible light is in the section of the spectrum called "near
infrared". This begins where visible light ends and again occupies a
very small part of the total spectrum-less than 1/10 25 . (3)

Is infrared light good for anything?
Yes, but this time it's no use to look around because you can't see it
with the naked eye. However you can easily feel it: the warmth you feel
on your face when you look up on a bright sunny summer or spring day is
caused by infrared radiation coming from the sun.

The sun's infrared radiation is what
carries the thermal energy that keeps Earth warm. It too is as
essential for life as visible light is. And the fascinating thing is
that our sun was apparently created just to serve for these two
purposes, because these two kinds of light make up the greatest part of
sunlight.

And the third part of sunlight? Is
that of any benefit? You can bet on it. This is "near ultraviolet
light" and it makes up the smallest fraction of sunlight. Like all
ultraviolet light, it is highly energized and it can cause damage to
living cells. The sun's ultraviolet light however is the "least
harmful" kind since it is closest to visible light. Although
overexposure to solar ultraviolet light has been shown to cause cancer
and cellular mutations, it has one vital benefit: the ultraviolet light
concentrated in such a miniscule band (4) is needed for the synthesis
of vitamin D in humans and other vertebrates. (Vitamin D is necessary
for the formation and nourishment of bone: without it, bones become
soft or malformed, a disease called rickets that occurs in people
deprived of sunlight for great lengths of time.)

In other words, all the radiation
emitted by the sun is essential to life: none of it is wasted. The
amazing thing is that all this radiation is limited to a 1/10 25
interval of the whole electro- magnetic spectrum yet it is sufficient
to keep us warm, see, and allow all the chemical reactions necessary
for life to take place.

Even if all the other conditions
necessary for life and mentioned elsewhere in this book existed, if the
light radiated by the sun fell into any other part of the
electromagnetic spectrum, there could be no life on Earth. It is
certainly impossible to explain the fulfillment of this condition
having a probability of 1 in 10 25 with a logic of coincidence.

And if all this were not enough, light does something else: it keeps us fed, too! GOD is running everything! Praise Be To GOD !